Nicotine, the common name of nicotine, is an alkaloid existing in solanaceae plants, an important component of tobacco, and a representative of N-cholinergic receptor agonist, which has effects on N 1 and N2 receptors and the central nervous system. Nicotine, the main source of nicotine, exists not only in tobacco leaves, but also in the fruits of many solanaceae plants, such as tomatoes, Lycium barbarum and other plants, which are recognized as healthy foods beneficial to human body. Because of this, as early as the 1990s, the World Health Organization vigorously promoted "nicotine replacement therapy" to quit smoking all over the world, which replaced the nicotine obtained from cigarettes in the past, helped people overcome their dependence on cigarettes physically and psychologically, and increased the chances of success in quitting smoking by more than 1 times. Harm of nicotine Nicotine can make people addicted or dependent. Repeated use of nicotine can also increase heart rate, raise blood pressure and reduce appetite. Large doses of nicotine can cause vomiting and nausea, and in severe cases people will die. Nicotine can stimulate the contraction of peripheral blood vessels, accelerate the heartbeat, increase blood pressure and breathe faster, and promote the occurrence of cardiovascular diseases such as hypertension and stroke. When nicotine enters the body, it will be transmitted through the blood and can pass through the blood-brain barrier. It takes only 7 seconds to reach the brain on average after inhalation. The half-life of nicotine in human body is about 2 hours. The amount of nicotine obtained by smoking is influenced by many factors, including the quality of the cigarette, whether it is inhaled in a big mouth or not, and whether the filter is used.